JP6601929B1 - Cell balance device - Google Patents

Abstract

A cell balance device capable of performing cell balance control with reduced current consumption when the ignition is off. A cell balance device includes a plurality of series-connected switch elements and resistors connected in parallel to each battery cell, a capacity adjustment circuit capable of adjusting the capacity of each battery cell, and a processor. 40 and a watchdog unit 60 that monitors the processor 40 and resets the processor 40 when the processor 40 is abnormal. The processor 40 transitions to a sleep state with the ignition off of the vehicle, and controls the switch element 11 in the sleep state to adjust the capacity of each battery cell 210. The processor 40 increases the capacity of each battery cell 210. At the time of adjustment, the number of battery cells 210 that are discharged simultaneously is set to a predetermined number so that the current flowing through the processor 40 becomes less than a predetermined value. [Selection] Figure 1

Description

  The present invention relates to a cell balance device.

  An assembled battery mounted on a vehicle such as a hybrid vehicle is configured by connecting a plurality of battery cells. In such an assembled battery, when the capacity of each battery cell is greatly different, when the assembled battery is charged, the battery cell having a large capacity may be overcharged. Therefore, in the assembled battery, it is desirable that the capacity of each battery cell is adjusted to be substantially uniform.

  For example, Patent Document 1 discloses a control circuit that adjusts the capacity of a battery cell even after charging and discharging of the assembled battery is completed.

Japanese Patent No. 3991620

  When charging / discharging the assembled battery is completed, that is, when the vehicle ignition is off, when performing cell balance control to adjust the capacity of the battery cell, the cell balance control can be executed with reduced current consumption. Is desirable.

  An object of the present invention made in view of such a viewpoint is to provide a cell balance device capable of performing cell balance control with reduced current consumption when the ignition is off.

In order to solve the above problem, a cell balance device according to a first aspect is:
A cell balance device that performs cell balance control on an assembled battery including a plurality of battery cells connected in series,
A plurality of series-connected switching elements and resistors connected in parallel to each battery cell; and a capacity adjustment circuit capable of adjusting the capacity of each battery cell by discharging each battery cell;
A processor for controlling the switch element;
A watchdog unit that monitors the processor, resets the processor when the processor is abnormal, and stops monitoring the processor when a current flowing through the processor is less than a predetermined value;
The processor shifts to a sleep state with the ignition off of the vehicle on which the cell balance device is mounted, and controls the switch element in the sleep state to adjust the capacity of each battery cell,
When adjusting the capacity of each battery cell, the processor sets the number of battery cells to be discharged simultaneously to a predetermined number so that the current flowing through the processor is less than the predetermined value.

  According to the cell balance device according to the first aspect, it is possible to execute the cell balance control in a state where the current consumption is reduced when the ignition is off.

It is a block diagram which shows the structural example of the battery apparatus which concerns on one Embodiment, and a cell balance apparatus. It is a figure for demonstrating operation | movement of the current detection circuit of FIG. It is a figure which shows an example of the relationship between the voltage of a battery cell, and SOC. It is a flowchart which shows an example of the timing of the cell balance control by the cell balance apparatus which concerns on one Embodiment. It is a flowchart which shows an example of the procedure of the cell balance control by the cell balance apparatus which concerns on one Embodiment. It is a figure for demonstrating an example of the procedure of the cell balance control by the cell balance apparatus which concerns on one Embodiment. It is a flowchart which shows another example of the timing of cell balance control. It is a perspective view which shows the battery apparatus which concerns on one Embodiment.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a battery device 1 and a cell balance device 100 according to an embodiment. The battery device 1 includes a cell balance device 100, an assembled battery 200, and a relay 300. The cell balance device 100 is connected to the assembled battery 200. The cell balance device 100 performs cell balance control on the assembled battery 200. In this specification, “cell balance control” refers to adjusting the capacity of the battery cells 210-1 to 210-5 so that the capacity of the battery cells 210-1 to 210-5 included in the assembled battery 200 is substantially uniform. Means control. Details of the cell balance control will be described later.

  The cell balance device 100, the assembled battery 200, the relay 300, and the load 400 shown in FIG. 1 are a vehicle equipped with an internal combustion engine such as a gasoline engine or a diesel engine, or a hybrid vehicle that can travel with the power of both the internal combustion engine and an electric motor. Or the like.

  The assembled battery 200 includes a plurality of battery cells 210-1 to 210-5 connected in series. Hereinafter, the battery cells 210-1 to 210-5 may be simply referred to as the battery cell 210 when it is not necessary to distinguish between them. Although FIG. 1 shows a case where the assembled battery 200 includes five battery cells 210-1 to 210-5, the number of battery cells 210 included in the assembled battery 200 is not limited to five. The assembled battery 200 may include an arbitrary number of battery cells 210 of two or more.

  The assembled battery 200 can supply power to the load 400. Further, the assembled battery 200 can be charged by regeneration when the vehicle on which the cell balance device 100 is mounted is decelerated. The assembled battery 200 may be rechargeable by a commercial AC power source.

  The battery cell 210 may be a secondary battery. The battery cell 210 is, for example, a lithium ion battery or a nickel metal hydride battery, but is not limited thereto, and may be another secondary battery. Although the battery cell 210 of this embodiment is 2.4V, it is not specifically limited.

  Relay 300 is connected between assembled battery 200 and load 400. The relay 300 switches the connection between the assembled battery 200 and the load 400. When the vehicle on which the cell balance device 100 is mounted is ignition on, the relay 300 is controlled to be turned on by the cell balance device 100. When the vehicle on which the cell balance device 100 is mounted is turned off, the relay 300 is controlled to be turned off by the cell balance device 100. In the present embodiment, the relay 300 includes a relay 301 and a relay 302 connected in series (see FIG. 8).

  The load 400 is various electric devices mounted on a vehicle on which the cell balance device 100 is mounted. The load 400 can operate by receiving power from the assembled battery 200.

  The cell balance device 100 includes a capacity adjustment circuit 10, a voltage detection circuit 20, a current detection circuit 30, a processor 40, a storage unit 50, and a watch dog unit 60.

  The capacity adjustment circuit 10 can adjust the capacity of the battery cells 210-1 to 210-5 by discharging the battery cells 210-1 to 210-5 independently. The capacity adjustment circuit 10 includes switch elements 11-1 to 11-5, resistors 12-1 to 12-5, and chip beads 13-1 to 13-6. In FIG. 1, the switch elements 11-1 to 11-5 are indicated as “SW”.

  The switch element 11-1 and the resistor 12-1 are connected in series. The switch element 11-1 and the resistor 12-1 connected in series are connected in parallel with the battery cell 210-1. The switch element 11-1 is controlled by the processor 40. When the switch element 11-1 is controlled to be turned on, the battery cell 210-1 is discharged via the switch element 11-1 and the resistor 12-1. When the battery cell 210-1 is discharged, the capacity of the battery cell 210-1 is reduced.

  Similarly, the switch element 11-2 and the resistor 12-2 connected in series are connected in parallel with the battery cell 210-2. The switch element 11-3 and the resistor 12-3 connected in series are connected in parallel with the battery cell 210-3. The switch element 11-4 and the resistor 12-4 connected in series are connected in parallel with the battery cell 210-4. The switch element 11-5 and the resistor 12-5 connected in series are connected in parallel with the battery cell 210-5.

  Further, chip beads 13-1 to 13-5 are connected between the respective switch elements 11-1 to 11-5 and the positive electrodes of the battery cells 210-1 to 210-5. A chip bead 13-6 is connected between the resistor 12-5 and the negative electrode of the battery cell 210-5. The chip beads 13-1 to 13-6 are inductors, and have a function of protecting against current fluctuations or a filter against high frequency noise.

  Hereinafter, the switch elements 11-1 to 11-5 may be simply referred to as the switch element 11 if it is not necessary to distinguish between them. In addition, the resistors 12-1 to 12-5 may be simply referred to as the resistor 12 when it is not necessary to distinguish between them. Further, the chip beads 13-1 to 13-6 may be simply referred to as chip beads 13 when it is not necessary to distinguish them.

  The switch element 11 may be a semiconductor switch, for example. The switch element 11 is controlled to be turned on by being driven to be turned on by the processor 40.

  The voltage detection circuit 20 detects each voltage of the battery cells 210-1 to 210-5. The voltage detection circuit 20 is electrically connected to the positive electrodes of the battery cells 210-1 to 210-5. The voltage detection circuit 20 is electrically connected to the negative electrodes of the battery cells 210-1 to 210-5.

  The voltage detection circuit 20 is based on the difference between the voltage of the wiring connected to the positive electrode of the battery cell 210-1 and the voltage of the wiring connected to the negative electrode of the battery cell 210-1. Can be detected. Similarly, the voltage detection circuit 20 can detect the voltages of the battery cells 210-2 to 210-5. The voltage detection circuit 20 outputs the detected voltage of the battery cells 210-1 to 210-5 to the processor 40.

  The current detection circuit 30 is not charged / discharged from the assembled battery 200, and the battery cells 210-1 to 210-5 are assumed to have the same potential when the cell balance device 100 is not performing the cell balance control of the assembled battery 200. The voltage of two points between any two adjacent battery cells 210 is detected, and the current flowing through the assembled battery 200 is detected based on the voltage of the two points. The current detection circuit 30 outputs the detected current flowing through the assembled battery 200 to the processor 40. The current detection circuit 30 detects a current based on the resistance value of the bus bar 702 (see FIG. 8) without using a shunt resistor as a component for detecting a current. The current detection circuit 30 detects the temperature in the vicinity of the bus bar 702 and corrects the resistance value of the bus bar 702 based on the temperature in order to ensure the accuracy of current detection.

  The current detection circuit 30 in the present embodiment detects the voltage as described above, and is supplied with driving power from the detection location. In order to drive the current detection circuit 30 of the present embodiment, 4 V or more is necessary. Therefore, the battery cell 210-1 and the battery cell 210- can secure a voltage of 4 V or more even when the assembled battery 200 is in the lower limit SOC state. Two voltages between 2 are detected (see FIG. 1).

  Note that the current detection circuit 30 detects the voltage between the battery cell 210-1 and the battery cell 210-2 is an example, and the present invention is not limited to this. As described above, the position where the current detection circuit 30 detects the voltage may be a location where the voltage driven by the current detection circuit 30 can be secured, and the current detection circuit 30 is located between the two adjacent battery cells 210. You may detect the voltage between points. Alternatively, the voltage detected by the current detection circuit 30 may be a voltage between two points between the positive electrode of the battery cell 210-1 having the highest potential in the assembled battery 200 and the relay 300. Alternatively, the current detection circuit 30 detects the voltage between two points between the negative electrode of the battery cell 210-5 having the lowest potential and the ground when the driving power of the current detection circuit 30 is supplied from VCC. Also good. In other words, it is only necessary to have a portion having the same potential in a state where there is no charge / discharge from the assembled battery 200 and the cell balance device 100 is not performing the cell balance control of the assembled battery 200.

  The current detection circuit 30 detects the voltage between the battery cell 210-1 and the battery cell 210-2 via the chip bead 31 and the chip bead 13-2. The chip bead 31 is also an inductor like the chip bead 13 and has a function of protecting against current fluctuations or a filter for high frequency noise. In the present embodiment, the chip beads 13-2 are shared by cell balance control and current detection.

  With reference to FIG. 2, the detection of the current of the assembled battery 200 by the current detection circuit 30 will be described. FIG. 2 is an enlarged view of the current detection circuit 30, the battery cell 210-1, and the battery cell 210-2.

  As shown in FIG. 2, of the two points on the wiring connecting the battery cell 210-1 and the battery cell 210-2, the first node 501 is a current detection circuit via the wiring 511 to which the chip beads 31 are connected. 30. The second node 502 is connected to the current detection circuit 30 via the wiring 512 to which the chip beads 13-2 are connected.

  The first node 501 and the second node 502 are connected by a bus bar 702 (see FIG. 8). The bus bar 702 may be an aluminum bus bar, for example. The resistance value of the aluminum bus bar is, for example, about 0.03 mΩ. The first node 501 and the second node 502 have the same potential when the assembled battery 200 is not charged / discharged and the cell balance device 100 is not performing the cell balance control of the assembled battery 200. Is charged and discharged, a minute voltage (for example, about 0.8 μV) is generated between the two points.

  The current detection circuit 30 stores the resistance value of the bus bar 702 as a known value. The current detection circuit 30 calculates the current flowing through the bus bar 702 by dividing the voltage that is the difference between the potential of the first node 501 and the potential of the second node 502 by the resistance value of the bus bar 702. Since the current flowing through the bus bar 702 is equivalent to the current flowing through the assembled battery 200, the current detection circuit 30 causes the assembled battery 200 to be detected by detecting the potentials of the first node 501 and the second node 502 in this manner. The flowing current can be detected.

  Again, with reference to FIG. 1, the component of the cell balance apparatus 100 is demonstrated.

  The processor 40 is communicably connected to each component of the cell balance device 100. The processor 40 may output a control instruction to each component and obtain information from each component.

  The processor 40 stores the voltages of the battery cells 210-1 to 210-5 acquired from the voltage detection circuit 20 in the storage unit 50. The processor 40 may cause the storage unit 50 to store the voltages of the battery cells 210-1 to 210-5 when the relay 300 is turned off and the assembled battery 200 is in an open state.

  The processor 40 causes the storage unit 50 to store the current flowing through the assembled battery 200 acquired from the current detection circuit 30.

  The processor 40 controls on / off of the switch element 11. The processor 40 drives the switch element 11 to turn it on, thereby discharging the battery cells 210 connected in parallel to the switch element 11. In FIG. 1, the control lines from the processor 40 to the switch elements 11-1 to 11-5 are not shown in order to improve readability.

  The processor 40 adjusts the capacity of the battery cell 210 by discharging the other battery cell 210 so that the voltage of the other battery cell 210 approaches the voltage of the battery cell 210 having the lowest voltage. The processor 40 can calculate the adjustment amount of the capacity of the other battery cell 210 based on the difference between the voltage of the battery cell 210 having the lowest voltage and the voltage of the other battery cell 210. The processor 40 causes the capacity adjustment circuit 10 to adjust the capacity of the battery cell 210 based on the calculated adjustment amount.

  The processor 40 refers to the table associating the relationship between the voltage and capacity of the battery cell 210 stored in the storage unit 50, and determines the capacity of the battery cell 210 having the lowest voltage and the capacity of the other battery cells 210. The difference can be calculated. The processor 40 can calculate a discharge current that flows through the battery cell 210 when the switch element 11 is turned on to discharge the battery cell 210 from the voltage of the battery cell 210 and the resistance value of the resistor 12. The processor 40 adjusts the capacity from the difference between the capacity of the battery cell 210 having the lowest voltage and the capacity of the other battery cell 210 and the discharge current flowing through the battery cell 210 when the switch element 11 is turned on. The time for which the discharge current is allowed to flow can be calculated.

  The processor 40 may use a predetermined voltage value instead of using the actual voltage value of the battery cell 210 when calculating the discharge current. For example, when the relationship between the voltage of the battery cell 21 and the SOC is the relationship shown in FIG. 3, the voltage fluctuation of the battery cell 21 is small when the SOC is in the range of about 40 to 90%. In this case, for example, the voltage value of the battery cell 21 when the SOC is 80% may be set as a predetermined voltage value, and the discharge current may be calculated from this voltage value and the resistance value of the resistor 12.

  The processor 40 continuously outputs a P-RUN signal to the watchdog unit 60 during the normal operation of the processor 40. The P-RUN signal is a signal indicating that the processor 40 is operating normally. The P-RUN signal is, for example, a pulse signal having a predetermined cycle and duty ratio, but may be another signal.

  When the processor 40 receives the reset signal from the watchdog unit 60, the processor 40 resets the operation. The processor 40 does not output the P-RUN signal when it enters an abnormal state that does not operate normally, such as freeze or runaway. Since the processor 40 receives the reset signal from the watchdog unit 60 after a predetermined time has elapsed since the P-RUN signal is no longer output, the processor 40 can reset the operation in the abnormal state.

  The storage unit 50 is connected to the processor 40 and stores information acquired from the processor 40. The storage unit 50 may function as a working memory for the processor 40. The storage unit 50 may store a program executed by the processor 40. The storage unit 50 is configured by, for example, a semiconductor memory, but is not limited thereto, and may be configured by a magnetic storage medium or may be configured by another storage medium. The storage unit 50 may be included in the processor 40 as a part of the processor 40.

  The storage unit 50 may store a table that associates the relationship between the voltage of the battery cell 210 and the capacity of the battery cell 210. The storage unit 50 may store a table that associates the relationship between the voltage of the battery cell 210 and the SOC of the battery cell 210. Since the capacity of the battery cell 210 and the SOC are in a proportional relationship, the processor 40 can calculate the other if either the capacity or the SOC is known.

  The watchdog unit 60 outputs a reset signal to the processor 40 when the P-RUN signal cannot be acquired from the processor 40 for a predetermined time.

  The watchdog unit 60 monitors whether the processor 40 is in a sleep state or a normal state in addition to a function (abnormality monitoring function) for monitoring whether the processor 40 is operating normally by receiving a P-RUN signal. ing. The watchdog unit 60 monitors the current flowing from the VCC power source to the processor 40 and the voltage detection circuit 20, and if the current is less than a predetermined value, the processor 40 is in the sleep state and stops the abnormality monitoring function. While the current from the power source continues to be monitored, the device itself enters the power saving mode. Thereafter, when the processor 40 returns to the normal state and the current flowing through the processor 40 exceeds a predetermined value, the watchdog unit 60 also returns to the normal mode and resumes the abnormality monitoring function.

  As described above, the watchdog unit 60 stops operating in the sleep state, so that the current consumption corresponding to the current flowing through the watchdog unit 60 can be reduced when the ignition is turned off. The predetermined value may be about 1 mA, for example.

(Cell balance control timing)
The timing of cell balance control will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the timing of cell balance control by the cell balance apparatus 100 according to the present embodiment.

  The cell balance device 100 performs the flow shown in FIG. 4A in the normal state. The normal state is a state in which a program for detecting the temperature and overvoltage of the assembled battery 200 and a program for calculating the SOC and SOH of the assembled battery 200 are operating in the processor 40. The cell balance device 100 performs the flow shown in FIG. 4B in the sleep state. Here, the sleep state means a state in which the processor 40 operates with low power consumption. In this sleep state, the processor 40 can perform cell balance control, which will be described later, in a state where the program for detecting the temperature and overvoltage and the program for calculating the SOC and SOH are stopped. The processor 40 transitions to this sleep state after the ignition is turned off.

  First, the process of the cell balance device 100 in the normal state will be described with reference to FIG.

  When the ignition is turned on, the processor 40 of the cell balance device 100 determines whether or not a predetermined time has elapsed (step S201). The predetermined time may be about 10 msec, for example. If it is determined that the predetermined time has not elapsed (No in step S201), the processor 40 repeats the process in step S201.

  If it determines with predetermined time having passed (Yes of step S201), the processor 40 will acquire the electric current of the assembled battery 200 which the electric current detection circuit 30 detected (step S202). The processor 40 acquires the voltage of the battery cell 210 detected by the voltage detection circuit 20 (step S203).

  The processor 40 executes other control (step S204), and returns to the process of step S201.

  Next, the process of the cell balance device 100 in the sleep state will be described with reference to FIG.

  When the ignition is turned off, the processor 40 of the cell balance device 100 executes cell balance control (step S301).

  Thus, the cell balance apparatus 100 according to the present embodiment does not execute the cell balance control in the normal state, but performs the cell balance control in the sleep state. That is, the cell balance device 100 performs cell balance control in the sleep state in which the current detection circuit 30 does not detect the current flowing through the assembled battery 200, and the normal state in which the current detection circuit 30 detects the current flowing through the assembled battery 200. In the state, cell balance control is not executed. Thereby, the detection of the current of the assembled battery 200 by the current detection circuit 30 in the normal state is not affected by the cell balance control. This point will be described in detail below.

  First, as a premise, the processor 40 needs to transmit the current value of the assembled battery 200 and the total voltage of the assembled battery 200 to the vehicle-side controller at a predetermined cycle (for example, 20 msec). For this reason, when the time constant of the CR filter in the current detection circuit 30 is large with respect to a predetermined period (for example, 15 msec), current detection, voltage detection, and cell balance control are sequentially performed within the predetermined period. It becomes difficult. For example, this problem becomes significant when the time constant is 1/2 or more of the predetermined period.

  Therefore, it is conceivable to perform cell balance control and current detection in parallel. However, as shown in FIG. 1 of the present embodiment, in this embodiment, the chip beads 13-2 are energized when the cell balance control is performed, and also when the current detection circuit 30 detects the current. Therefore, if cell balance control and current detection are performed simultaneously, the following problem occurs. That is, in a state where the battery cell 210-2 is discharged and the cell balance control is executed without discharging the battery cell 210-1, a current flows through the chip beads 13-2 due to the discharge of the battery cell 210-2. . When a voltage between the first node 501 and the second node 502 is detected in this state, a potential difference is generated between the first node 501 and the second node 502 due to the energization of the chip beads 13-2. As a result, there arises a problem that the current value is erroneously detected. For example, even when there is no discharge from the assembled battery 200, the current detection circuit 30 detects a current.

That is, in current detection in which a voltage between two points is detected and a current value is calculated, when the current is detected in a state where the battery cell 210 on one side is discharged, one measurement point is detected. On the other hand, an erroneous detection of the current value caused by detecting a low potential at the other measurement point is caused.
On the other hand, according to the cell balance device 100 according to the present embodiment, the processor 40 operates in a normal state where the current detection circuit 30 needs to periodically detect a current (from ignition on to ignition off). Prohibit execution of balance control. Then, in the sleep state (between ignition off and ignition on), the capacity adjustment circuit 10 adjusts the capacity of the battery cell 210. Thereby, the cell balance control by the cell balance apparatus 100 according to the present embodiment does not affect the current detection of the assembled battery 200 by the current detection circuit 30.

  Moreover, according to the cell balance device 100 according to the present embodiment, the cell balance device 100 detects two voltages between any two adjacent battery cells 210 of the plurality of battery cells 210, and the two points. A current detection circuit 30 that detects a current flowing through the assembled battery 200 based on the voltage of By detecting the current using such a current detection circuit 30, a current sensor such as a Hall element becomes unnecessary, and the cell balance device 100 can reduce the current detection means of the assembled battery 200. it can.

(Cell balance control)
An example of the procedure of cell balance control will be described with reference to FIGS.

  First, an example of the procedure of cell balance control by the cell balance apparatus 100 according to the present embodiment will be described with reference to the flowchart shown in FIG.

  The processor 40 of the cell balance device 100 monitors whether or not the ignition is turned off (step S401). If it is determined that the ignition is not turned off (No in step S401), the processor 40 repeats the process in step S401.

  If it is determined that the ignition is turned off (Yes in step S401), the processor 40 starts execution of cell balance control, and executes the processes of steps S402 to S405 shown in FIG. In the ignition off state, the current flowing through the processor 40 is less than a predetermined value. Therefore, the watchdog unit 60 stops the abnormality monitoring function and enters the power saving mode.

  The processor 40 reads the voltage of the battery cell 210 detected by the voltage detection circuit 20 and stored in the storage unit 50 when the ignition is on (step S402). In the present embodiment, the processor 40 performs cell balance control after the ignition is turned off, based on the voltage of the battery cell 210 when the ignition is turned on, which is close to the open circuit voltage.

  The processor 40 selects the battery cell 210 having the highest voltage among the battery cells 210-1 to 210-5 (step S403).

  The processor 40 turns on the switch element 11 connected in parallel to the battery cell 210 having the highest voltage, and discharges the battery cell 210 having the highest voltage. Thereafter, the processor 40 discharges one battery cell 210 at a time. That is, the processor 40 does not turn on two or more switch elements 11 at the same time, and repeats control to turn on only one switch element 11, thereby adjusting the capacity of the battery cells 210-1 to 210-5. (Step S404).

  As a result of adjusting the capacity, the processor 40 determines whether or not the difference between the voltage of the battery cell 210 having the highest voltage and the voltage of the battery cell 210 having the lowest voltage is within a predetermined range (step S405).

  If it is determined that the difference between the voltage of the battery cell 210 having the highest voltage and the voltage of the battery cell 210 having the lowest voltage is not within the predetermined range (No in step S405), the processor 40 returns to step S404 and returns to the battery. The process of adjusting the capacity of the cell 210 is continued.

  If it is determined that the difference between the voltage of the battery cell 210 having the highest voltage and the voltage of the battery cell 210 having the lowest voltage is within the predetermined range (Yes in step S405), the processor 40 ends the cell balance control.

  As described in the description of step S404, the processor 40 discharges only one battery cell 210 in the cell balance control. That is, the processor 40 drives only one switch element 11 in the cell balance control. Therefore, the current flowing through the voltage detection circuit 20 is smaller than when driving a plurality of switch elements 11 simultaneously. Therefore, the current flowing through the processor 40 can be less than a predetermined value even when performing the cell balance control. When the current flowing through the processor 40 is less than the predetermined value, the watchdog unit 60 can maintain the stopped state, and thus the processor 40 can be maintained in the sleep state. As a result, the cell balance device 100 can execute cell balance control when the ignition is turned off in a state in which the current consumption corresponding to the current flowing through the watchdog unit 60 and the processor 40 is reduced.

  This point will be described in detail. As described above, the watchdog unit 60 monitors the current flowing through the processor 40 and determines whether the processor 40 is in a normal state or a sleep state. Therefore, when the processor 40 performs the cell balance control in the sleep state after the ignition is turned off, if the plurality of switch elements 11 are driven and the current flowing through the processor 40 exceeds a predetermined value, the watchdog unit 60 returns to the normal mode and resumes the abnormality monitoring function. In that case, since the processor 40 is in a sleep state and has stopped transmitting the P-RUN signal, the watchdog unit 60 determines that the processor 40 is abnormal, and resets and restarts the processor 40. . As a result, the current consumption of the processor 40 is increased.

  In the present embodiment, by performing cell balance control so that the current flowing through the processor 40 is maintained below a predetermined value, the processor 40 can be prevented from being reset, and an increase in power consumption of the processor 40 can be prevented.

  Although the processor 40 has been described as discharging only one battery cell 210 in the cell balance control, the number of battery cells 210 to be discharged simultaneously is not limited to one. For example, even if a predetermined number of battery cells 210 are discharged at the same time, if the current flowing through the processor 40 is less than a predetermined value, the processor 40 may discharge the predetermined number of battery cells 210 simultaneously.

  Subsequently, an example of a procedure of cell balance control by the cell balance apparatus 100 according to the present embodiment will be described in more detail with reference to FIG. The cells A to E shown in FIG. 6 correspond to the battery cells 210-1 to 210-5 shown in FIG.

  When the ignition is turned off, the processor 40 of the cell balance device 100 reads the voltages of the cells A to E stored in the storage unit 50 when the ignition is turned on. FIG. 6A shows an example of the voltages of the cells A to E read by the processor 40.

  In the example shown in FIG. 6A, the voltage VE of the cell E is the highest voltage among the voltages of the cells A to E. Further, the voltage VD of the cell D is the lowest voltage among the voltages of the cells A to E. The voltage VB of the cell B is the second highest voltage among the voltages of the cells A to E.

  The processor 40 selects the cell E having the highest voltage, and first discharges the cell E for a predetermined time. The predetermined time is a preset time, and may be, for example, about 60 seconds. When discharged for a predetermined time, the voltage of the cell E drops by ΔV as shown in FIG. After discharging the cell E for a predetermined time and then discharging the cell E for a predetermined time, the processor 40 determines whether the voltage of the cell E is lower than the voltage of the cell B having the next highest voltage.

  Next, when the voltage of the cell E is not lower than the voltage of the cell B even if the cell E is discharged for a predetermined time, the processor 40 continues to discharge the cell E for a predetermined time. FIG. 6B shows a state in which the control for discharging the cell A every predetermined time (each 60 seconds) is repeated four times.

  In the state shown in FIG. 6B, when the cell E is discharged for a predetermined time next time, the voltage of the cell E becomes lower than the voltage of the cell B. In this case, the processor 40 discharges the cell B having the next highest voltage after the cell E for a predetermined time. FIG. 6C shows a state where the cell B is discharged for a predetermined time.

  Thereafter, the same processing is repeated, and when the voltages of the cells A to E fall within a predetermined range, the processor 40 ends the cell balance control. The predetermined range may be a voltage range in which the cells A to E drop by one discharge for a predetermined time, that is, a range of ΔV shown in FIG.

  FIG. 6D shows an example of the voltages of the cells A to E when the cell balance control is finished. In the example shown in FIG. 6D, the voltages of the cells A to E are within the range D. The range D is within the range of ΔV shown in FIG.

  In the process shown in FIG. 6, when there are a plurality of battery cells 210 having the same voltage magnitude, the processor 40 gives priority to, for example, the battery cell 210 with a smaller number (for example, the battery cell in the example shown in FIG. 1). The discharging may be performed in preference to the 210-1 side.

  According to the cell balance device 100 according to the present embodiment, when the capacity adjustment circuit 10 adjusts the capacity of the battery cell 210 when the vehicle is ignition off, the processor 40 causes the current flowing through the processor 40 to be less than a predetermined value. As described above, the number of battery cells 210 that are discharged simultaneously is set to a predetermined number. As a result, the watchdog unit 60 can be kept in a stopped state, and the processor 40 can be maintained in the sleep state. As a result, the cell balance device 100 according to the present embodiment can execute cell balance control when the ignition is turned off in a state in which the current consumption corresponding to the current flowing through the watchdog unit 60 and the processor 40 is reduced.

  Further, for example, Japanese Patent Application Laid-Open No. 2006-164882 discloses a capacity adjustment device that divides battery cells into groups and performs cell balance control for each group. When cell balance control is performed when the ignition is off in this way, if the ignition is turned on before the cell balance control is completed, the vehicle may start with a large voltage difference between the battery cells. . According to the cell balance device 100 according to the present embodiment, since the battery cell 210 having the highest voltage is discharged first, the voltage difference between the battery cells 210 is reduced even if the ignition is turned on before the cell balance control is completed. Yes.

  In the above embodiment, the configuration in which the cell balance control is performed after the ignition is turned off has been described. However, the time constant of the CR filter in the current detection circuit 30 is sufficiently small (for example, 5 msec), and the processor 40 has a predetermined period (for example, 20 msec). ), The current detection and the cell balance control may be performed in order as shown in FIG. The flowchart of FIG. 7 will be described below.

  When the ignition is turned on, the cell balance device 100 determines whether or not a predetermined time has elapsed (step S101).

  If it is determined that the predetermined time has elapsed (Yes in step S101), the cell balance device 100 turns off the cell balance control (step S102).

  The cell balance device 100 detects the current flowing through the assembled battery 200 (step S103). The cell balance device 100 detects the voltage of the battery cell 210 included in the assembled battery 200 (step S104).

  The cell balance device 100 turns on the cell balance control and executes the cell balance control (step S105). The cell balance control period in FIG. 7 is set to a short time that falls within the predetermined period (for example, 5 msec to 10 msec), and after the predetermined time has elapsed, the cell balance control is turned off in step S102. That is, in the cell balance control described with reference to FIG. 7, the discharge is performed little by little while the vehicle is running, instead of discharging over time after the ignition is turned off. Note that the discharge order of the cell voltages is performed from the highest cell voltage as described in FIG.

  The assembled battery 200 in this embodiment is accommodated in the case 600 as shown in FIG. In FIG. 8, the locations where the battery cells 210-1 to 210-5 are arranged are indicated by dotted frames. Bus bar 701 connects the bus bar connected to relay 300 and the positive electrode of battery cell 210-1. The bus bar 702 connects the battery cell 210-1 and the battery cell 210-2. The bus bar 703 connects the battery cell 210-2 and the battery cell 210-3. The bus bar 704 connects the battery cell 210-3 and the battery cell 210-4. The bus bar 705 connects the battery cell 210-4 and the battery cell 210-5. The bus bar 706 connects the battery cell 210-5 and the ground.

  In addition, the bus bar 701 has a terminal 701a that detects the cell voltage of the battery cell 210-1 and further serves as a discharge route for cell balance control. The bus bar 702 also has terminals 702a and 702b as similar terminals, the bus bar 703 also has terminals 703a and 703b as the same terminals, the bus bar 704 also has terminals 704a and 704b as the same terminals, and the bus bar 705. Also have terminals 705a and 705b as similar terminals, and the bus bar 706 also has a terminal 706b as similar terminals.

  In the present embodiment, the first node 501 is a terminal 702b, and the second node 502 is a terminal 702a. As described above, the terminals 702a and 70b also function as terminals for detecting a voltage in the current detection circuit 30.

  Although one embodiment according to the present disclosure has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. For example, in this embodiment, the current of the assembled battery 200 is detected by measuring the voltage between two points on the same bus bar. However, the battery cell 210 is a laminate cell type, and the electrode tab is in direct contact. When connecting in series, the voltage between two points of one electrode tab may be detected. Thus, the location for detecting the voltage is not limited to the bus bar, but may be a wiring including the electrode tab.

  Accordingly, it should be noted that these variations or modifications are included in the scope of the present disclosure. For example, the functions included in each means can be rearranged so as not to be logically contradictory, and a plurality of means can be combined into one or divided.

DESCRIPTION OF SYMBOLS 100 Cell balance apparatus 1 Battery apparatus 10 Capacity adjustment circuit 11 Switch element (SW)
DESCRIPTION OF SYMBOLS 12 Resistance 13 Chip bead 20 Voltage detection circuit 30 Current detection circuit 31 Chip bead 40 Processor 50 Memory | storage part 60 Watchdog part 200 Battery assembly 210 Battery cell 300 Relay 301, 302 Relay 400 Load 501 1st node 502 2nd node 511 Wiring 512 Wiring 600 Case 701, 702, 703, 704, 705, 706 Bus bar 701a-705a terminal 702b-706b terminal

Claims (5)

A cell balance device that performs cell balance control on an assembled battery including a plurality of battery cells connected in series,
A plurality of series-connected switching elements and resistors connected in parallel to each battery cell; and a capacity adjustment circuit capable of adjusting the capacity of each battery cell by discharging each battery cell;
A processor for controlling the switch element;
A watchdog unit that monitors the processor, resets the processor when the processor is abnormal, and stops monitoring the processor when a current flowing through the processor is less than a predetermined value;
The processor shifts to a sleep state with the ignition off of the vehicle on which the cell balance device is mounted, and controls the switch element in the sleep state to adjust the capacity of each battery cell,
The cell balance device, wherein when the capacity of each battery cell is adjusted, the processor sets a predetermined number of battery cells to be discharged simultaneously so that a current flowing through the processor is less than the predetermined value. The cell balance device according to claim 1,
The said battery is a cell balance apparatus which discharges the said battery cell one by one, when adjusting the capacity | capacitance of each said battery cell. In the cell balance device according to claim 1 or 2,
When adjusting the capacity of each battery cell, the processor discharges the battery cell having the highest voltage first. The cell balance device according to claim 3, wherein
The said battery is a cell balance apparatus which discharges every predetermined time, when adjusting the capacity | capacitance of each said battery cell. The cell balance device according to claim 4, wherein
The processor discharges the battery cell for the predetermined time and then discharges the battery cell for the predetermined time. When the voltage of the battery cell is lower than the voltage of the next highest battery cell, A cell balance device that discharges a battery cell having a high height for the predetermined time.